Study subjects were randomized in order to receive a single dose of either paracetamol (Perfalgan, Bristol Myers Squibb, Itxassou, France), 1 gr in 100 ml normal saline, or morphine (0.1 mg/kg in 100 ml normal saline) in a blinded fashion. The study drugs was written in a paper which is folded four times and covered with sealed bands for allocation concealment. The study nurse withdrew one of the drugs from a box. And they were prepared by the study nurse and administered by the second nurse blinded to the study. Study drugs were identical in color and appearance. Subjects with who needed rescue drug because of inadequate pain relief were received fentanyl 1 μg/kg intravenously.